In known electronic musical instruments such as electronic pianos, it has hitherto been customary practice to provide a key arrangement like that shown in FIG. 1. As can be seen in FIG. 1, a key a is supported at a supporting point c of a frame b such that the key can rotate about an axis passing through the supporting point c perpendicular to the plane of the drawing. A tension spring d is resiliently coupled to the base end portion of the key for providing a force for restoring the key to its undepressed position.
This conventional key arrangement has the disadvantage that the relationship of the depression force to the stroke or displacement of the key a has the characteristic curve shown in FIG. 2. As a result of this relationship the player can only experience the touch feeling produced by the gradual and monotonous increase of the force required to depress the key from the beginning to the end of a depression stroke. The player is unable to experience a touch feeling like that produced by an actual piano key during depression.